Germ-line gene therapy and the medical imperative.

Somatic cell gene therapy has yielded promising results. If germ cell gene therapy can be developed, the promise is even greater: hundreds of genetic diseases might be virtually eliminated. But some claim the procedure is morally unacceptable. We thoroughly and sympathetically examine several possible reasons for this claim but find them inadequate. There is no moral reason, then, not to develop and employ germ-line gene therapy. Taking the offensive, we argue next that medicine has a prima facie moral obligation to do so.     

Improving assignment preference through interspersing additional problems: Brief versus easy problems

College students were exposed to a control mathematics assignment containing 16 three-digit by two-digit multiplication (3×2) problems and two experimental assignments that contained 16 equivalent 3×2 problems and six additional interspersed problems. On one experimental assignment, 4-digit plus 4-digit problems (4+4) were interspersed. On the other experimental assignment, 2-digit divided by 1-digit with whole number answers problems (2/1) were interspersed. When given a choice, significantly more students choose the 2/1 assignment over the control and 1+4 assignment. Students also ranked the 2/1 sheet as requiring less time to complete than the control or 4+4 assignment but no differences were found on assignment difficulty rankings between the 4+4 and 2/1 assignments. No differences were found on accuracy levels or rates of responding on the target 3×2 problems across assignments. Results showed that interspersing additional problems that take relatively less time to complete may be more important for altering student preference for assignments than interspersing easier problems. Discussion focuses on schedules of reinforcement and resource efficient procedures for increasing student preference for assignment without compromising curricula integrity.     

Use of speech-modulated noise adds strong “bottom-up” cues for phonemic restoration

When deleted segments of speech are replaced by extraneous sounds rather than silence, the missing speech fragments may be perceptually restored and intelligibility improved. This phonemic restoration (PhR) effect has been used to measure various aspects of speech processing, with deleted portions of speech typically being replaced by stochastic noise. However, several recent studies of PhR have used speech-modulated noise, which may provide amplitude-envelope cues concerning the replaced speech. The present study compared the effects upon intelligibility of replacing regularly spaced portions of speech with stochastic (white) noise versus speech-modulated noise. In Experiment 1, filling periodic gaps in sentences with noise modulated by the amplitude envelope of the deleted speech fragments produced twice the intelligibility increase obtained with interpolated stochastic noise. Moreover, when lists of isolated monosyllables were interrupted in Experiment 2, interpolation of speech-modulated noise increased intelligibility whereas stochastic noise reduced intelligibility. The augmentation of PhR produced by modulated noise appeared without practice, suggesting that speech processing normally involves not only a narrowband analysis of spectral information but also a wideband integration of amplitude levels across critical bands. This is of considerable theoretical interest, but it also suggests that since PhRs produced by speech-modulated noise utilize potent bottom-up cues provided by the noise, they differ from the PhRs produced by extraneous sounds, such as coughs and stochastic noise.     

The mechanist and the snail

Conclusion Using an example drawn from evolutionary biology, I have shown that distinct, competing explanations may nonetheless postulate identical networks of causal processes and interactions. It follows from this that to provide a causal explanation is to do more than describe a network of causal processes and interactions. In the example given, it seems that the proffered explanations also purport to describe probabilistic causal relations of the sort rejected by Salmon.     

Effects of Organizational Citizenship Behaviours: Evidence from Production Supervisors

Based on a sample of production workers in a textile firm, supervisory ratings of employee performance were found to be influenced by supervisors' perceptions of employees' organizational citizenship behaviours as well as by employees' objectively measured performance. Regression analysis indicated that supervisory ratings were influenced by two dimensions of organizational citizenship behaviour — conscientiousness and altruism — as well as by objective performance. These three variables explained 53% of the variance in ratings. A third dimension of OCB, sportsmanship, did not affect supervisory ratings.     

Hemispheric asymmetries in the identification of band-pass filtered letters

Processing of band-pass filtered letters in the left versus right cerebral hemispheres (LH vs. RH) was examined. The present experiments constituted a partial replication of a study in which Peterzell, Harvey, and Hardyck (1989) found no hemispheric differences in accuracy or reaction time (RT) as a function of spatial frequency. However, methodological limitations of their study (e.g., the possibility that subjects were engaged in a detection, not identification, task) may have obscured possible hemispheric differences. We addressed these problems in the present study, obtaining significant hemisphere × spatial frequency interactions for RT andd', with RH advantages at low frequencies and LH advantages at high frequencies; however, these effects were not large in magnitude and were often restricted to particular dependent variables, stimulus sizes, and so forth. Hemispheric differences in response bias were also found.     

Questions of criteria: Reply to Peterzell (1997)

In a reply to our report on hemispheric differences in processing band-pass filtered letters (Christman, Kitterle, & Niebauer, 1997), Peterzell (1997) argues that our results are not attributable to hemispheric asymmetries in spatial frequency processing. Rather, Peterzell argues that factors such as response criteria and stimulus visibility can account for our results. We argue that our results are attributable (at least in part) to hemispheric asymmetries in spatial frequency processing, while at the same time we acknowledge the potential influence of other factors in the determination of hemispheric differences.     

Cochlear implants and the claims of culture? A response to Lane and Grodin

Because I reject the notion that physical characteristics constitute cultural membership, I argue that, even if the claim were persuasive that deafness is a culture rather than a disability, there is no reason to fault hearing parents who choose cochlear implants for their deaf children.